1. Field of Invention
The present invention relates to the field of combined yarns including a metallic component that are preferably cut and/or abrasion resistant, to composite yarns including such combined yarns, and to the application of air interlacing technology to the manufacture of such combined yarns.
2. Discussion of the Background
The present invention relates to yarns useful in the manufacture of various types of protective garments such as cut and puncture resistant gloves, aprons, and glove liners, and in particular to composite yarns useful for the manufacture of these garments that include a metallic strand as a part of the yarn construction.
Composite yarns that include a metallic yarn component, and cut-resistant garments prepared therefrom are known in the prior art. Representative patents disclosing such yarns include U.S. Pat. Nos. 4,384,449 and 4,470,251. U.S. Pat. No. 4,777,789 describes composite yarns and gloves prepared from the yarns, in which a strand of wire is used to wrap the core yarn. The core components of these prior art composite yarns may be comprised of cut-resistant yarns, non-cut resistant yarns, fiberglass and/or a metallic strand, such as stainless steel. One or more of these components may also be used in one or more cover yarns that are wrapped around the core yarn.
It is well known in the art to manufacture such composite yarns by combining an inherently cut-resistant yarn with other strands using wrapping techniques. For example, these yarns may use a core construction comprising one or more strands that are laid in parallel relationship or, alternatively, may include a first core strand that is overwrapped with one or more additional core strands. These composite yarns can be knit on standard glove-making machines with the choice of machine being dependent, in part, on the yarn size.
Wrapping techniques are expensive because they are relatively slow and often require that separate wrapping steps be made on separate machines with intermediate wind up steps. Further, those techniques require an increased amount of yarn per unit length of finished product depending on the number of turns per inch used in the wrap. Generally, the greater the number of turns per inch, the greater the expense associated with making the composite yarn. When the yarn being wrapped is high performance fiber, this cost may be high.
Knitted gloves constructed using a relatively high percentage of high performance fibers do not exhibit a soft hand and tend to be stiff. This characteristic is believed to result from the inherent stiffness of the high performance fibers. It follows that the tactile response and feedback for the wearer is reduced. Because these gloves typically are used in meat-cutting operations around sharp blades, it would be desirable to maximize these qualities in a cut-resistant glove.
The use of a stainless steel or other wire strand, as at least a part of the core yarn, provides enhanced cut resistance in garments, such as gloves. However, various disadvantages of prior art composite yarns incorporating a stainless steel or other wire strand have been noted. For example, there has been, with prior art yarn construction techniques, a risk of breakage of some of the wire strands, resulting in exposed wire ends that can penetrate the user's skin.
Also, during knitting, the wire component of the yarn tends to kink and form knots when subjected to the forces normally incurred during knitting. Wire strands alone cannot be knitted for this reason. While the problem is somewhat lessened by combining the wire strand or strands with other fibers as taught in the prior art, the wire component still tends to kink, knot or break, thereby lessening its usefulness in cut-resistant garments.
Processes involving treatment of yarns with air jets are well-known in the prior art. Some of these treatments are used to create textured yarns. The term “texturing” refers generally to a process of crimping, imparting random loops, or otherwise modifying continuous filament yarn to increase its cover, resilience, warmth, insulation, and/or moisture absorption. Further, texturing may provide a different surface texture to achieve decorative effects. Generally, this method involves leading yarn through a turbulent region of an air-jet at a rate faster than it is drawn off on the exit side of the jet, e.g., overfeeding. In one approach, the yarn structure is opened by the airjet, loops are formed therein, and the structure is closed again on exiting the jet. Some loops may be locked inside the yarn and others may be locked on the surface of the yarn depending on a variety of process conditions and the structure of the air-jet texturizing equipment used. A typical airjet texturizing devices and processes is disclosed in U.S. Pat. No. 3,972,174.
Another type of airjet treatment has been used to compact multifilament yarns to improve their processibility. Flat multifilament yarns are subjected to a number of stresses during weaving operations. These stresses can destroy interfilament cohesion and can cause filament breakages. These breakages can lead to costly broken ends. Increasing interfilament cohesion has been addressed in the past by the use of adhesives such as sizes. However, air compaction has enabled textiles processors to avoid the cost and additional processing difficulties associated with the use of sizes. The use of air compaction for high strength and non-high strength yarns is disclosed in U.S. Pat. Nos. 5,579,628 and 5,518,814. The end product of these processes typically exhibits some amount of twist.
Other prior art, such as U.S. Pat. Nos. 3,824,776; 5,434,003 and 5,763,076, and earlier patents referenced therein, describe subjecting one or more moving multifilament yarns with minimal overfeed to a transverse air jet to form spaced, entangled sections or nodes that are separated by sections of substantially unentangled filaments. This intermittent entanglement imparts coherence to the yarn, avoiding the need for twisting of the yarns. Yarns possessing these characteristics are sometimes referred to in the prior art as “interlaced” yarns, and at other times as “entangled” yarns.
While intermittent air entanglement of multifilament yarns has been used to impart yarn coherence, the application of this technology to combining yarns including a cut resistant yarn component and a wire component has not been recognized except in U.S. Pat. No. 6,381,940. This U.S. patent requires the use of two separate multi-filament yarns combined with one or more metal strands. The two separate multi-filament yarns are combined around the metal strand(s) by air-interlacing. However, in order to provide adequate coverage of the one or more metal strands, this patent requires the use of at least two non-metallic strands during the air-interlacing process. Thus, there is still a need for a composite yarn that includes a wire component that does not significantly kink and form knots during knitting, combined with only a single multifilament or spun yarn, and for the resultant yarns and garments manufactured therefrom.